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HomeMy WebLinkAbout016 - Water Design ReportDiscount Tire 5889 E Valley Center Road Bozeman, Montana, 59718 Geocode Water Main Extension and Replacement Engineering Report 6814 Greenwood Avenue N T 206.522.9510 Seattle, WA 981093 www.pacland.com Prepared By: Bill Fortunato, P.E. August 2025 Per the requirements of the Montana Department of Environmental Quality (DEQ) Water Main Extension and Replacement Certified Checklist, this engineering report has been prepared to address Sections 1.1.1 through 1.1.14 of DEQ-1. These sections are addressed below: 1.1.1. General Information: a. Description of the existing water works and sewer facilities: • An 8” ductile iron water main runs north-south through the center of the site, and a 24” polyethylene sewer pipe runs from the southeast to northwest along the eastern edge of the site. b. Identification of the municipality or area served: • City of Bozeman c. Name and mailing address of the owner, developer and official custodian: • Owner/Developer: Discount Tire (Colten Ellsworth) • 20225 N Scottsdale Rd • Scottsdale, AZ 85255 • Engineer/Applicant: PACLAND (Bill Fortunato) • 6814 Greenwood Avenue N • Seattle, WA 98103 d. Imprint of professional engineer’s seal: 1.1.2. Extent of water works system, including: a. Description of the nature and extent of the area to be served: • The proposed scope of work involves removing an existing hydrant that would limit the available development area and installing a new 26 LF 6” water main to provide fire protection for the proposed development. The existing easement would be revised to include the new hydrant and remove the portion around the existing easement. b. Provisions for extending the water works system to include additional areas: • No provisions for extending the water system to additional areas are proposed. c. Appraisal of the future requirements for service, including existing and potential industrial, commercial, institutional, and other water supply needs: • Future requirements for the service will remain unchanged. Adjacent properties are currently developed and served by existing water mains and fire hydrants. The proposed hydrant is only required in order to provide fire protection for the proposed commercial development. 1.1.3. Alternate plans: Where two or more solutions exist for providing public water supply facilities, each of which is feasible and practicable, discuss the alternate plans. Give reasons for selecting the one recommended, including financial considerations, and a comparison of the minimum classification of water works operator required for operation of each alternative facility. • The alternate plan evaluated was to retain the existing hydrant and utilize it for fire protection. However, this would push the proposed building footprint to the east and limit the developable area, and would also run counter to direction from the City of Bozeman to locate the building as close as possible to the drive aisle that runs north-south on the west side of the building. 1.1.4. Site Conditions: Soil, ground water conditions, and foundation problems, including a description of: a. The character of soil through which water mains are to be laid. • On-site soils have been classified as generally being Topsoil overlaying Sandy Lean Clay, medium stiff to very stiff, with sand and scattered gravels and traces of organics (CL) overlaying a layer of Clayey Gravel with Sand, medium dense to very dense (GC), overlaying a layer of Well Graded Gravel with Silt and Sand, saturated, medium dense to very dense, with sand and clay lenses (GW-GM). b. Foundation conditions prevailing at sites of proposed structures. • On-site soils are suitable for foundations with a maximum net allowable bearing pressure of 3,500 pounds per square foot. Proposed structure will utilize shallow footings and a floor slab. c. The approximate elevation and flow direction of ground water in relation to subsurface structures. • During geotechnical investigation, groundwater was typically encountered between 6’ and 7.5’ below existing grade. Based on existing topography, it is assumed that groundwater flows to the north and west. 1.1.5. Water use data, including: a. A description of the population trends as indicated by available records, and the estimated population which will be served by the proposed water supply system or expanded system, a minimum of 20 years in the future in five year intervals or over the useful life of the critical structures and equipment. • The proposed main extension will not affect the water supply system, as it will be replacing a similar existing hydrant. b. Present water consumption and the projected average and maximum daily demands or peak instantaneous demand where appropriate, including fire flow demand (see Section 1.1.6). • Per the City of Bozeman Design and Construction Standards, Section 4.2.7, the required fire flow based on the project land use (Central Business) is 4,000 gallons per minute. The standards reference the International Fire Code, which states that fire flows are to be based on a 20 psi residual pressure, for a duration of 2 hours (based on building size). Since the proposed fire hydrant would replace the existing hydrant, no change would be experienced in the demand. • The fire flow value provided in the referenced section above are guidelines only and may not be indicative of the requirements for specific developments or buildings. Fire demand for specific developments shall be in accordance with International Fire Code (IFC) and as approved by the COB Fire Chief. c. Present and/or estimated yield of the sources of supply. • The City of Bozeman relies on snowpack and surface water for its water supply, receiving 80% of its water from the Gallatin Mountains and 20% from developed springs in the Bridger Mountains. In 2020, total annual metered production was approximately 6,822 ac- ft. d. Unusual occurrences. • The proposed water main extension is only expected to be utilized during emergency fire conditions. e. Current estimated percent of unaccounted water for the system and the estimated reduction of unaccounted water after project completion, if applicable, i.e., project is to replace aged water mains, leaking storage, or other improvements that will result in reduced water loss. • The proposed water main extension is not anticipated to reduce water loss. No significant impact to the amount of unaccounted water is anticipated. 1.1.6. Flow Requirements a. Hydraulic analyses based on flow demands and pressure requirements (See Section 8.2.1). • As outlined in 1.1.5.b, fire flow demand for the project is 4,000 gpm at a residual pressure of 20 psi for 2 hours. b. Fire flows, when fire protection is provided, meeting the recommendations of the fire protection agency in which the water system is being developed, or in the absence of such a recommendation, the fire code adopted by the State of Montana. Documentation from the fire protection agency may be required if the flow requirements vary significantly from typical values. • Per a fire flow test performed on April 03,2025 at the existing on-site fire hydrant, a flow of 1,600 gpm at 114.2 psi (including a 10% factor of safety) was measured. The calculated flow for a pressure of 20 psi would be 3,744 GPM. This flow rate is below the required fire flow value of 4,000 gpm identified in 1.1.6.a. however it is also noted in that section that the provided value is a guideline. Minimal friction losses due to pipe lengths, valves, bends, etc. are anticipated, but will not significantly affect the available fire flow. no change would be experienced in the demand, it is expected that no change would be experienced in the demand. 1.1.7. Sources of water supply Describe the proposed source or sources of water supply to be developed, the reasons for their selection, and provide information as follows: 1.1.7.1 Surface water sources a. Hydrological data, stream flow and weather records. b. Safe yield, including all factors that may affect it. c. Maximum flood flow, together with approval for safety features of the spillway and dam from the appropriate reviewing authority. d. Description of the watershed, noting any existing or potential sources of contamination (such as highways, railroads, chemical facilities, land/water use activities, etc.) which may affect water quality. e. Summarized quality of the raw water with special reference to fluctuations in quality, changing meteorological conditions, etc. f. Source water protection issues or measures, including erosion and siltation control structures that need to be considered or implemented. g. A source water assessment report for surface water sources. • No surface water sources are appropriate for the proposed water main extension. 1.1.7.2 Ground water sources a. Sites considered. b. Advantages of the site selected. c. Elevations with respect to surroundings. d. Probable character of formations through which the source is to be developed through nearby well logs; e. Geologic conditions affecting the site, such as anticipated interference between proposed and existing wells. f. Summary of source exploration, test well depth, and method of construction; placement of liners or screen; test pumping rates and their duration; water levels and specific yield; water quality. g. Sources of possible contamination, such as sewers and sewage treatment/disposal facilities, highways, railroads, landfills, outcroppings of consolidated water-bearing formations, chemical facilities, waste disposal wells, agricultural uses, etc. h. A preliminary assessment for proposed ground water sources that may be under the direct influence of surface water, prepared in accordance with PWS-5, "Assessment of Ground Water Sources Under the Direct Influence of Surface Water". i. A source water assessment report prepared in accordance with PWS-6. • No ground water sources are appropriate for the proposed water main extension. 1.1.8. Proposed treatment processes Summarize and establish the adequacy of proposed processes and unit parameters for the treatment of the specific water under consideration. Alternative methods of water treatment and chemical use should be considered as a means of reducing waste handling and disposal problems. Bench scale tests, pilot studies, or demonstrations will generally be required to establish adequacy for some water quality standards. • Treatment for the City of Bozeman’s water system is provided by two treatment plants, the Sourdough Creek Water Treatment Plant and the Lyman Creek Water Treatment Plant. Approximately 5,000+ water quality samples per year are taken from the distribution system, with 25,000+ water quality tests are performed each year. Per water quality reports, system test results indicate water being within the acceptable range for all contaminants evaluated. 1.1.9. Sewage System available Describe the existing or proposed sewage collection system and sewage treatment works, with special reference to their relationship to existing or proposed water works structures which may affect the operation of the water supply system, or which may affect the quality of the supply. • An existing sewer system will service the proposed commercial development. However, the proposed water main extension is solely related to fire flow, and is not affected by the sewage system. 1.1.10. Waste Disposal Discuss the various wastes from the water treatment plant, their volume, proposed treatment, and disposal locations. If discharging to a sanitary sewer system, verify that the system, including any lift stations, is capable of handling the flow to the sewage treatment works and that the treatment works is capable and will accept the additional loading. • No discharge to the sanitary sewer system is proposed as part of the main extension. 1.1.11. Automation Provide supporting data justifying automatic equipment, including the servicing and operator training to be provided. Manual override must be provided for any automatic controls. Highly sophisticated automation may put proper maintenance beyond the capability of the plant operator, leading to equipment breakdowns or expensive servicing. Adequate funding must be assured for maintenance of automatic equipment. • No automation is proposed. 1.1.12. Project sites a. Discussion of the various sites considered and advantages of the recommended ones • No alternate sites were considered for the development. b. The proximity of residences, industries, and other establishments. • The project site is located within a commercial area. Hotels are adjacent to the property to the north and south. The site is also bounded by the I-90 off-ramp to the east and E Valley Center road to the west. No residential properties are present in the vicinity of the project site. c. Any potential sources of pollution that may influence the quality of the supply or interfere with effective operation of the water works system, such as sewage absorption systems, septic tanks, privies, cesspools, sink holes, sanitary landfills, refuse and garbage dumps, etc. • No sources of pollution are known. 1.1.13. Financing Provide financial information for new systems or significant improvements with economic impacts as required in Appendix A. • The proposed main extension is very minor in nature, and is not considered a significant system improvement to necessitate providing financial information as outlined in Appendix A of the Montana Circular DEQ 1. 1.1.14. Future extensions Summarize planning for future needs and services. • No future extensions are anticipated. The proposed main extension will provide fire hydrant coverage for the proposed development.